Hydraulic controlling apparatus



. 2 sheets-sheet 1 .Q m l A G O O llIL zum? 1./,3

Afro/@Mfr YF. v. BROWN 2,119,416

HYDRAULIC CONTROLLING APPARATUS Filed oct. 14, 1935 2 sheets-sheet 2 May 31, 193s.

Patented May 31., 1938 PATENT OFFICE HYDRAULIC CONTROLLING APPARATUS Francis Victor Brown, London, England, assignorl to Automotive Products Company Limited, London, England Application October 14, 1935, Serial No. 45,003 In Great Britain February 16, 1935 Claims.

This invention relates to hydraulically actuated apparatus and controls particularly for aircraft, and it has for its object to provide an improved method of operation as well as a new con- 5 struction of apparatus which is more efficient and reliable than those installations which have hitherto been proposed.

The improved method of actuating a hydraulically controlled motor cylinder of an aircraft consists in interposing between the master cylinder and the motor cylinder, a valve which vis spring-influenced so as normally to assume a position in which operation of the master cylinder tends to move the motor cylinder in a preferred to safe direction, positive adjustment of the valve being required for otherwise actuating the motor cylinder.

The invention further provides an improved construction of hydraulic controlling system for an aircraft, comprising in combination with a master cylinder, a change-over valve whereby liquid under pressure can be fed through either one of a plurality of delivery pipes, a pair of such pipes conveniently being provided and the valve V being arranged so that pressure liquid delivered by the master cylinder can be passed along either of said pipes', the other pipe being automatically relieved of pressure.

The invention further provides a hydraulic controlling system ,comprising in combination a single acting master cylinder, a double acting motor cylinder, and a change-over valve whereby the delivery of the master cylinder can be connected `to either side of the motor cylinder, that side of the motor cylinder not being fed with liquid from the master cylinder conveniently being automatically allowed to discharge through the change-over valve.

Moreover the invention also provides a controlling system comprising in combination witha single acting master cylinder, the piston of which is associated with a free packing cup adapted to cover` a breathing aperture in the cylinder wall at the beginning of its stroke, a motor cylinder having one boundary of its Working space arranged for limited lost motion, whereby the first Vpart of the-master cylinder stroke is effected with only a low pressure load. The change-over valve which is associated with the master cylinder is preferably influenced to return automatically to a preferred setting after use in any other setting, thus making reasonably sure that any unauthorized actuation of the master cylinder will only tend to move the motor cylinder in the preferred direction.

CII

One form of spar attachment pin system for an aircraft is illustrated in the accompanying drawings as an example ofthe present invention, and in said drawings:-

Figure 1 is a sectional side elevation showing' 5 the master cylinder unit and one of the spar attachment pins;

Figure 2 is a part sectional plan of the master cylinderunit shown in Figure 1;

Figure 3 is a fragmentary sectional elevation 10 showing the control valve in the position required for withdrawing `the spar pins;

Figure 4 is a fragmentary section through that end portion of the attachment pin remote. from the nose of the plunger, the latter being in its 15 hydraulically Withdrawn position; and

Figure 5 is a view corresponding to Figure 4 except that the plunger has been mechanically withdrawn, as for example when the 'hydraulic part of the system is disabled. 20

The master cylinder unit comprises a horizontally arranged cylinder barrel I0 secured in the lower part of a reservoir casting II and protrud.- ing therefrom, said cylinder barrel being enclosed in a barrel cover I2 attached conveniently to the 25 reservoir at one end and closed at its other end to form the cylinder head I3. In order to provide a pressure-tight joint at this part a packing Washer I4 is inserted, this being conveniently of the internal gas pressure type, and being ar` 30 ranged to bear against a reinforcing vring I5 secured to the cylinder tube I0. The cylinder head I3 is transversely bored at I6 to receive a frusto-conical plug I1 forming a change-over valve, said plug being urged against its conical 35 bore I6 by means of a compression spring- I8 (see Figure 2) and a ball thrust bearing I9. Said plug I'I is also formed with a pair of tangential grooves 20 and 2l the first of which is adapted to connect a main delivery passage 22 communicating 40 with the master cylinder I0 to either one of a pair of outlet pipes 23 and 24, the other of said outlet pipes .being automatically connected with the reservoir II by way of the groove 2|, through a passage 25 bored in the cylinder head I3, and then 45 through the annular space 26 between the cylinder I0 and the barrel cover I2. The valve plug Il is operated by means of an axial stem 21 which extends through the wall of the cylinder head I3 where it is surrounded by a `exible packing washer 28 of substantially U-shaped radial crosssection. The valve plug Il, moreover, is normally urged against its seating I6 by pressure produced in the master cylinder Il), a subsidiary passage 29 being formed in the cylinder head I3 55 for this purpose. The cylinder head itself is composed of an outer shell 30 of light metal having an interior block 3 I of phosphor bronze or other material suitable for the valve bore I6.

The wall 32 of the reservoir II opposite the open end of the master cylinder barrel is formed with an elongated auxiliary bore 33 extending coaxially with said master cylinder I0, and arranged to accommodate slidably an auxiliary piston 34 connected with the main piston by a hollow tapering sleeve 35'. 'I'his sleeve 35 also forms a deep Well 36 containing the ball-shaped end of a push rod 31, by means of which a main piston 38 and the auxiliary piston 34 can be moved t0- wards the cylinder head I3. The auxiliary piston' 34 is provided with a resilient packing ring 39 of rubber or equivalent, which, of course, need be only capable of withstanding the pressure head in the reservoir, but the main piston 38 which has to bear-the comparatively high operating pressure is equipped with a rubber or other flexible piston cup 49 which is quite imperforate, but is normally held against the piston 38 by means of va conical compression spring 4I disposed within the master cylinder I and acting upon the outer portion of a cup-shaped thrust member- 42. At the rear of the piston cup 40 the piston member 38 is formed with a number of longitudinal liquid passages 43, the forward ends of which communicate with an annular groove 44 of V-shaped radial cross-section, said groove accommodating a correspondingly shaped valve ring 45 which thus provides a smooth surface on the head of the piston for engagement with the back of the piston cup 4U. The centre part of the thrust member 42 co-operating with the piston cup 40 is curved in diametral cross-section as will be seen in Figure 1 so as to produce inthe rubber or equivalent material when pressure is applied by the compression spring, a pressure intensity which increases smoothly towards the centre of the cup. 'Ihis construction has the main advantage that it permits the piston cup 49 to collapse readily during the return stroke of the piston and thus provide ample room for the release of the valve ring. The open end of the master cylinder I 8 communicates, of course, with the reservoir through an opening v46, as well as with the' auxiliary cylinder 33, while a breather hole or holes 41 is or are formed in the wall of the master cylinder at a place adjacent to but just in advance of the rim of the main pistonl cup 40, this j hole or holes serving to equalize the pressure in Las the master cylinder I 0 and reservoir I I when .-the vpiston 38 is lcompletely retracted, thus automatically replenishing the liquid in the operative v Apart `of the system should leakage have taken place. At its other smaller end the conical compression spring 4| acts upon a differential delivery valve 48 of the known form adapted to maintain a slight pressure in the motor cylinder or cylinders, for example the spar pin unit, the barrel of which'is indicated at 49 in the drawings. y

The lling aperture 5I) of the reservoir is conveniently bell-shaped, andis fitted with a valve which permits the ingress of air but prevents the escape of liquid. The master unit can conveniently be installed on the leading edge of an aircraft wing which latter is indicated at 52 in Figure 1, the cylinder head I3 nfacing rearwardly, and for such an installation the push rod 3| operating the main piston 38 can conveniently be connected at its forward end to a curved operating" lever 53, the projecting part of the pin 1I.

push rod 3| being surrounded by a flexible boot 54. The operating lever is pivoted at 65 to a pair of arms 55 formed on or carried by the reservoir casting |I, the rear end of said lever being fitted with a convenient handle 56, while downward movement of said handle is limited by a toggle linkage 51 fitted with a coiled tension spring 58 adapted to return the lever 53 automatically yto its raised position in which the main piston 38 is completely retracted. The control valve I1 in the cylinder head I3 is spring-influenced to assume its safe" position, in which actuation of the lever 53 tends to move the plunger 59 of the spar pin unit 49 to its bolted position, but it is connected with a push button 60 conveniently placed on the leading edge 52 of the wing, and arranged so that the spar pin plungers 59 can only be Withdrawn by the master cylinder unit when the push button 60 is depressed and the operating handle 56 is pulled downwardly, the valve I1 then being in the position shown in Figure 3. With the valve I1 in its other position as shown in Figure 1, downward movement of the operating handle 56 only tends to' force the spar pin plungers 59 further out. For actuating the Valve plug I1 the spindle 21 is fitted with an arm 6I, which is pivotally connected to a push rod 62 carrying the push button 60, a coiled compression spring 63 being adapted to return said button automatically to the above-mentioned safe position.

For use with thev master cylinder unit above described, a convenient construction of spar pin is shown in Figures 1, 4 and 5,-and comprises an elongated tubular barrel forming the main body of the assembly and tted internally with a pin bolt 1I which is slidable in the axial direction. The nose or plunger 59 of this bolt, which plunger serves to co-act between the folding part 12 and the fixed part 13 of the aircraft wing, is of enlarged diameter, and rits into 'a bore 14 formed in a combined reinforcing tube and iixing flange attached to the end of the cylinder barrel. For lightness and ease of manufacture the central part 1| of the bolt pin is tubular, While its tail end 16 is solid and is of square cross-section, the corners being screw-threaded as indicated at 11 to co-act with a manual retracting hand nut 18. Thev adjacent end of the outer barrel is closed by an internal screw-threaded cap 19 conveniently provided with a locking washer 88, said cap being formed With a square hole through which the tail 16 of the bolt 1| passes, while a collar 8| also formed with a square hole to rlt slidably upon the tail 16 of the. pin is anchored axially to the hand nut 18, but is arranged with anexpanding ring 82 so that said nut 18 can freely rotate upon the tail 16 of the bolt, whereas the collar 8|4 is held against such rotation by its square hole. The collar 8| thus serves as a non-rotatable anchorage for an extensible bellows or boot 83, the other end of which is connected to the outside of the tubular barrel by a clip84. By this means, retracting movement of the pin bolt, irrespective of whether this movement is broughtv about hydraulically or mechanically, will move the screwthreaded tail out of the spring ,barrel and thus will serve as an indicator, while the boot 83 prevents the access of dirt into the screw-threads of thejpin and the interior oi' the unit.

The tail end of the barrel 49 accommodates a coiled compression spring 85, one end of which abuts against the closure cap 19, while the other engages a tail piston collar 86 secured to the At its other side this tail piston collar is fitted with a resilient washer or piston cup 81 which is, of course, annular in formation, and in radial cross-section is of substantially Y-shape, the tail portion 88 being adapted to engage in an undercut groove formed in the tail piston collar 85. The resilient cup 81 is, of course, truly cylindrical on its inner and outer surfaces, and is somewhat elongated in an axial direction so that the interior of the U-shaped part is disposed some distance from the part which is anchored in the undercut recess. This enables the piston cup to accommodate itself readilyv to inaccuracies and irregularities in the bore of the outer barrel lll. and also in the exterior surface of the pin bolt. A similar fitting 89 herein referred to as the head piston collar is attached to the pin bolt 1I immediately adjacent the plunger portion thereof, the washer or piston cup 90 in this case, however, being -directed oppositely. By this means a hydraulic cylinder space is formed between the interior of the outer barrel 1|) and the exterior of the bolt 1|, this space being divided into two portions 9| and 92 by a partition member in the form of a collar 93 slidably mounted with respect to both the ,outer barrel 49 and the bolt 1|, but being formed on its lperiphery with an annular groove 94 adapted to be engaged by a circumferential series of locking screws 95 extending radially inwards through the outer barrel.

a reinforcement ring being provided for their reception. The annular groove 94 is, however, considerably wider measured axially than the diameter of the screw tips, so that an appreciable longitudinal travel of the collar 93-amounting to, say three-sixteenths of an inchis permitted relative to thetubular barrel 49. At its ends the partition collar 93 is undercut, and is arranged to receive resilient cup washers 96 and 91 so as to form a pressure-tight sliding joint between the inner surface of the barrel and the exterior of the pin bolt. The two hydraulic compartments 9| and 92 are provided with pipe connections 98 and 99 respectively, which are joined to the pipes 23 and 24 respectively of the master cylinder unit. Where a plurality of spar pins are to be operated simultaneously, as for example in the nase of folding wing biplanes, the pipes 23 and 24 can be provided with branches |00 and |0| which lead to thehydraulic compartments of the other spar pin or pins. It Will be seen that when the valve |1 is in the safe position as shown in Figure 1. operation of the master cylinder will deliver pressurefluid into `the compartment 9| and will thus augment the tendency of the spring to return the plunger 59 to its operative posiion.

It is found that the slight axial play of the collar 93 permitted by the groove 94 is important for the proper operation of the unit, as this enables the first part of the master cylinder stroke to be effected at low pressure and thus enables the rim ofthe cup 4|) to pass the breathing aperture or apertures 41 before any considerable pressure is attained. Thus, by referring 'particularly to Figures 1 and 4, it .will be seen that when the puch button 50 is depressed and the lever 53 operated, pressure fluid will enter the compartment` Qfland will force the collar 86 to the left, at the same time compressing the spring 85 and withdrawing the-plunger 59 until it assumes the position indicated at 59a. At the same time the tail 'i6 is also moved through the cap 19 as shown in Figure 4. thus extending the boot 83 and provid- ,ing an indication that the plunger 59 is withdrawn.

During normal service the nut 18 is anchored upon the tail 16 by means of a split pin or equivalent locking means |02, which in the event of emergency can be fairly readily removed so as to permit the nut 18 to be rotated relative to the tail 16 and collar 8|, thus withdrawing the bolt 1| as shown in Figure 5. Inthis case the boot 83 does not expand but it is securely held against twisting by the engagement of the square hole in the collar 8| with the tail portion 16. This mechanical actuation is especially useful when the aircraft is being overhaulcd or repaired, as it may possibly happen that the spar pins require withdrawal, while the hydraulic system is drained or is otherwise inoperative.

It will be seen that the invention thus provide in particular an extremely compact and serviceable form of spar pin system which can read- Ily be installed, and which avoids the considerable inconvenience which is at present experienced in directly actuating the existing mechanical locking means` especially where such means are comparatively inaccessible The invention is not limited, however, to the example described, and the improved master cylinder may be used in conjunction with any double-acting motor cylinder or equivalent for providing a positive movement in either of two directions, while, of course, the multi-way valve used for directing the path of the pressure iluid delivered by a master cylinder need vnot be formed as part of the latter, but can, if desired, be included elsewhere in .the hydraulic system. Moreover, spar pin units in accordance with the invention can be operated by any suitable master cylinder arrangement, while other means may be employed for obtaining the lost motion effect.

What I claim is:-

1. In a hydraulic system for remotely controling hole in the master cylinder being uncovered by the master piston when the latter is in its completely retracted position so as to place the master cylinder space into connection with the reservoir, a motor cylinder, a pipe line connecting the master cylinder with the motor cylinder, a motor piston slidable in said motor cylinder, a sliding bolt secured to said piston and a wall in the motor cylinder, said wall having a limited f-ree movement in the motor cylinder so as to give way freely under the actiony of liquid delivered by the initial part of the movement of the master piston and thus prevent the rise of pressure in the master cylinder until after Athe master piston has welll covered the breathing bolt by liquid pressure, a master cylinder and master piston, a rservoir. a breathing hole in the master cylinder being uncovered by the master piston when the latter is in its completely retracted position so as to place the master cylinder space into connection with the reservoir, a motor cylinder, a pipe line connecting the master cylinder with the motor cylinder, a pair of motor pistons slidable in the motor cylinder, a sliding bolt holding the pistons in spaced relationship and a partition member disposed between said pistons, said partition member being slidable within limits in the cylinder so as to prevent the pressure from rising in the master cylinder until after the master piston has well cov-` ered the breathing hole.

3. In a hydraulic system for controlling a, sliding bolt by liquid pressure, a master cylinder and master piston, a cup packing upon the front of the master piston, a reservoir, a breathing hole in the master cylinder being uncovered by the packing cup of the master piston when the latter' is in its completely retracted position so as to place the master cylinder space into connection with the reservoir, a motor cylinder, a pipe line connecting the master cylinder with the motor cylinder, a motor piston slidable in said motor cylinder, a sliding bolt secured to said piston, a partition in the motor cylinder slidably mounted relative to both the sliding bolt and the motor cylinder, and means for limiting the movement between the partition and cylinder to a, small fraction of the stroke of the' motor piston, whereby the pressure is prevented from rising in the master cylinder until after the packing cup of the master piston has Well covered the breathing hole.

4. In a` hydraulic system for controlling a sliding bolt by liquid pressure, a. master cylinder and master piston, a reservoir, a breathing hole in the master cylinder being uncovered by the master piston when the latter is in its completely retracted position so as to place the master cylinder space into communication with the reservoir, a motor cylinder, a pair of motor pistons slidable in the motor cylinder, a sliding bolt vholding the pistons in spaced relationship, a partition member disposed between said pistons and slidable within limits in the cylinder, a valve,

a pair of pipe lines connecting the respective sides of the lmotor cylinder partition with the valve, and a pipe line connecting the master cylinder with the valve whereby pressure liquid can be fed to either side of the motor cylinder partition according to the direction in which the sliding bolt is to be moved, the free movement of the partition preventing the liquid pressure from rising inthe master cylinder until the master piston has moved well beyond the breathing hole.

5. In a hydraulic system for controlling a sliding bolt by liquid pressure, a master cylinder and master piston, a reservoir, a breathing hole in the master cylinder being uncovered by the master piston when the latter is in its completely retracted position so as to place the master cylinder space into connection with the reservoir, a motor cylinder, a pipe line connecting the master cylinder with the motor cylinder, a motor piston slidable in the motor cylinder, a sliding bolt secured to said piston, a partition member in the motor cylinder formed with a circumferential recess, a pin extending radially into the motor cylinder and engaging the recess so as to allow a limited axial movement of the partition member and thereby prevent thepressure from rising in the master cylinder until the masterpiston has moved well beyond the breathing `hole at the beginning of its stroke.

FRANCIS VICTOR BROWN. 

